In the field of ink jet printing, a common construction of the print head has included a plurality of ink drive elements and a plurality of associated nozzles to form a multiple nozzle print head. Additionally, certain printing devices comprise a plurality of single nozzle print heads wherein a drive element and an associated nozzle of simple unitary construction form each of the print heads which are spaced in a line across the printer and thereby print lines of dots in the process of printing the characters along a line thereof.
In the case of a multiple nozzle print head, such head usually assumes a frustum-like shape wherein a plurality of nozzles at the small end of the head are closely positioned in a vertical line for ejecting droplets of ink against a record medium for forming the characters. A plurality of drive elements are associated with the respective nozzles by means of fluid passageways or conduits and wherein the drive elements are arranged in circular manner at the large end of the print head.
In any event, the print head is caused to travel in back-and-forth or reciprocating manner across the printer and in a direction which is transverse or perpendicular to the direction of movementof the record medium to be printed. The droplets of ink are caused to be ejected through the nozzles by means of individual membranes controlled by drive elements in the form of piezoelectric crystals which are actuated to increase the pressure in the ink cavity and force the droplets of ink against the record medium.
When the print head is caused to be moved at high speeds back-and-forth across the printer, the head and the ink in the channels and passageways are subjected to extreme acceleration and deceleration forces at the ends of the line of printing and the flow of ink may be interrupted while being subject to these forces during the printing operation. The quality of printing and the reliablity of operation or functioning of the ink jet printer or recording device considerably and substantially depends on the ability of the print head to resist the effects of these acceleration and deceleration forces.
Representative prior art in ink jet printers includes German Pat. No. 2,262,106, (see U.S. Pat. No. 3,708,798) wherein a multiple nozzle ink jet print head includes an intermediate container through which the ink flows from the ink supply container to the print head nozzles. The intermediate container includes an air bubble wherein fluctuations of pressure and pressure shocks occurring in the supply system are absorbed to a certain degree and the reliability of functioning of the print head is improved.
German Pat. No. 2,543,397 (see U.S. Pat. No. 4,124,853) discloses damping means for compensating fluctuations of pressure in ink supply systems of printing devices. The damping means consists of a membrane which is arranged at the uppermost part of the common ink distributing means of the print head.